Field of the Invention
The present invention relates to a machine tool system and an opening stop position calculating device for calculating an opening stop position of a door that is opened for exchanging a workpiece of a machine tool.
Description of the Related Art
In order to manufacture workpieces at lower cost, automation and high speed operations for manufacturing have been sought. As one part thereof, an existing automation system for automating machining that is performed by using a machine tool is known. In such an automation system, not only machining itself, but exchange of workpieces (loading of non-machined workpieces and unloading of machined workpieces) is performed automatically. Exchange of the workpiece is carried out by a workpiece exchanging device. Further, when machining is carried out, it is necessary to close the door in order to prevent scattering of chips and cutting fluid, whereas when exchanging the workpiece, it is necessary to open the door so that the workpiece exchanging device can be moved inside the machine tool, and opening and closing of the door is carried out also automatically. Although a fluid pressure cylinder using hydraulic pressure or air may be used as a drive source for opening and closing the door, in this case, since it is difficult to control the position and speed of the door, it also is difficult to lower the speed immediately before the stop position of the door, and to accurately stop the door at an arbitrary position.
In Japanese Patent No. 4629392, opening and closing of a door at high speed by using a servomotor and a ball screw is disclosed. Because the door can be decelerated by the servomotor in the vicinity of an opening/closing terminus thereof even if the door is moved at a high speed, and because the door can be stopped at an arbitrary position, shocks at the opening/closing terminus can be reduced, and further, by opening the door only at a required width, it is possible to carry out opening and closing of the door at a higher speed. Consequently, the time required to open and close the door is shortened, and the cycle time can be made shorter as well.
Japanese Laid-Open Patent Publication No. 2010-228063 relates to a door, which is not a door (opening and closing door) that partitions the interior and exterior of a machine tool, but rather is a door disposed between a machining area in an interior part of a machine tool and a standby area of the tool. By changing the opening width of the door, the time required to open and close the opening and closing door is not wasted at the time of tool change, and thus, the machining time is shortened.